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The price of compromising on IAQ

Highlighting that uncontrolled movement of air within a building not only compromises the design intent of the HVAC system but also increases pollutants in a building that affect our mental and physical well-being, David O’Riley makes a case for continuous monitoring to obtain real-time data to enable remedial action.

The World Health Organization (WHO) describes the effect of indoor air pollutants on health as Sick Building Syndrome, which gives rise to eye, nose and throat irritation, dry mucous membrane and dry skin, erythema (skin redness), mental fatigue, headaches, a high frequency of airway infections and coughs, hoarseness and wheezing, itching and non-specific skin hypersensitivity, and nausea and dizziness. Common symptoms characterised by nasal dryness or congestion, such as a stuffy blocked nose or a runny nose, and also mental effects, such as difficulty in concentrating, can arise.

Just because you may be suffering from some of these symptoms does not necessarily mean that the environment in which you live and/ or work has Sick Building Syndrome. However, one thing is for certain – the climatic conditions across the GCC region, coupled with indifferent construction and poor quality maintenance, does make it highly probable.

As Professor DJ Clements-Croome of the School of Construction Management and Engineering, University of Reading, Reading, Berkshire, United Kingdom, has observed: “Temperature, relative humidity and air quality all affect the sensory system via thermo-receptors in the skin and the olfactory system (nasal passage). Air quality is mainly defined by the contaminants in the air. However, the most persistent memory of any space is often its odour. Strong, emotional, and past experiences are awakened by the olfactory sense. Odours can also influence cognitive processes that affect creative task performance, as well as personal memories and moods. Besides nitrogen and oxygen, the air contains particles and many chemicals that affect the efficiency of the oxygenation process in the blood, and ultimately, the air breathed affects thinking and concentration.”

With people in the Middle East typically spending more than 90% of their time in an air conditioned environment, the importance of indoor air quality (IAQ) is a matter of concern for governments, which is why regulatory requirements were put in place in Abu Dhabi and Dubai several years ago, although for some reason, enforcement has not yet been activated.

COMPROMISES TO IAQ

The pollutants in the air in a room will typically come from two main sources:

• Infiltrations into the building from outside, such as dust and other particulate matter, gases and fumes, (including volatile organic compounds), electrical particles, such as negatively and positively charged ions, biological agents and water vapour

• Those generated from within the building, such as Volatile Organic Compounds (VOCs) emitted from building and furnishing materials, flakes of skin, carbon dioxide (CO2) and a variety of other gases, particulates arising from poorly maintained electrical equipment, including HVAC systems and biological agents from mould growth

It is clear that with so many sources of pollution able to adversely affect the well-being of occupants, a building’s HVAC system needs to be not only of good design but also carefully installed, commissioned and supported by quality maintenance, if the occupants are to be adequately protected. Unfortunately, even if this were true, there is still the issue of poorly constructed buildings to contend with.

During the building design process, an HVAC engineer is required to make a number of assumptions about a building, one of which is that it is actually built to, or close to the consultant’s specification/drawings. Sadly however, we all know that this rarely happens in this part of the world, with the inevitable consequence that the HVAC system design is compromised even before it is installed.

THE EFFECT OF CO₂

CO2 is produced when people breathe. Each exhaled breath by an average adult contains 35,000-50,000 parts per million (ppm) of CO2 – 100 times higher than the average outdoor concentration.

In recent years, scientists and researchers have become ever-more aware of the growing significance of CO2 with respect to its effect upon the occupants of a building. According to the Canadian Centre for Occupational Health & Safety, health effects can become acute at higher exposure levels. For example, concentration levels of 7.5% lead to headaches, dizziness, restlessness, the feeling of an inability to breathe, sweating, malaise, increased heart rate, increased blood pressure and visual distortion.

Studies being carried out by the University of Reading in primary schools have shown that the CO2 levels vary from 800 ppm to almost 5,000 ppm. This finding is of particular concern, because primary schoolchildren spend several hours a day in the same room and, hence, the build-up of CO2 is most notable in the morning and in the afternoon. So far, the tests show that there is a relationship between CO2 levels and the effectiveness of some learning tasks.

Other relevant recent studies on schools include the work of Godwin & Batterman on IAQ in 64 Michigan primary and secondary schools, and Kim on respiratory symptoms, asthma, and allergen levels in Korean and Swedish schools.

A detailed study by Pawel Wargocki from the International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, shows that improving IAQ improves the performance of office work by adults and the performance of schoolwork by children.

By measuring the performance of individual tasks under controlled conditions, a relationship was established between the performance of schoolwork and classroom ventilation. The relationship suggests that doubling the fresh air supply rate to reduce the CO2 level improves the performance of schoolwork in terms of speed by about eight per cent, and under certain circumstances, up to 14% was observed.

The results of these experiments indicate that improving IAQ in classrooms by increasing the fresh air supply rate can substantially improve the performance of a wide range of tasks characteristic of schoolwork, from rule-based logical and mathematical tasks requiring concentration and logical thinking to language-based tasks requiring concentration and comprehension.

The experiments also revealed that the magnitude of the effects on performance of schoolwork is greater than for the performance of office work by adults, probably because children are more susceptible to environmental conditions and also because schoolwork is not quantified in monetary terms. Even so, the economic benefits from improved productivity of office workers resulting from improved IAQ considerably exceed the costs involved.

Another conclusion was that the risk of developing Sick Building Syndrome is reduced and perceived air quality is improved, when the ventilation rates are about 20l/s per person. The work also indicated that CO2 concentrations below 800 ppm are preferable. It has been found that Dubai regulations specify a maximum indoor CO2 concentration of 800 ppm.

THE CHALLENGESAddressing the problem of high levels of CO2 in a building in itself does not provide a solution to the wider issues of poor IAQ, but it is an important factor, particularly with respect to occupants’ mental and cognitive functions. From a comfort perspective, issues such as temperature and humidity are, for most people, the most important factors. If you feel comfortable, your body will be more relaxed, which will enable you to perform better. And if CO2 levels are correct, that performance will be even better still.

High levels of humidity, condensation and the subsequent presence of mould are an ever-present problem. Apart from the unsightly appearance of mould, the real danger to health is from mould spores, and, in particular, mycotoxins. Mycotoxins are produced when two or more mould species are present in close proximity. They are the mould’s defence mechanism, designed to kill other mould species. These are extremely dangerous to human health, often causing severe allergic reactions and having a lasting effect in the body’s immune system. Some mycotoxins are known to be carcinogenic.

Other pollutants to be considered are:

• VOCs: These are ever-present, typically leaching into the building’s atmosphere from paints, adhesives, cleaning products, soft and hard furnishings, clothing and electronic equipment. Damage to liver, kidney and the central nervous system are known health risks when exposed to unacceptable levels.

• Particulates: in this region, the most prevalent particulates are sand particles. The most common measurement is for particulates of less than 10 microns in size, but by far the most dangerous are those particles that are less than 2.5 microns in size. These particles are raised into the atmosphere from the desert by strong winds, and are known to cause irreversible damage to the lungs. They can also find their way into the blood stream.

To effectively mitigate all of these health risks, a multi-pronged approach is necessary, as there is no single action that can fix them all. Current regulations in the UAE and elsewhere call for IAQ measurement to be taken once or twice a year. However, the reality is that this is wholly inadequate if the intent is to mitigate the health risks. What is required is continuous monitoring, so that there is a constant stream of real-time data available to enable timely remedial action.

Even before continuous monitoring can be effective, however, there is the challenge of fixing the building. The low level of tradesmen skills, coupled with minimal quality oversight are two major factors that contribute to a building not being constructed in accordance with the consultant’s specifications, the other being the pursuit of profit above all other considerations. Trying to effect a solution by merely addressing shortcomings with the HVAC system is simply throwing good money after bad. What is required is a holistic approach to the problem.

PRACTICAL SOLUTIONS

The first step is to commission a survey of the building and the HVAC system. The focus must be on identifying factors that impact IAQ. The resultant report should provide a route map that enables the client to take a structured approach to achieving an IAQ standard that ideally will exceed what is required by the local regulations.

The uncontrolled movement of air within a building not only compromises the design intent of the HVAC system, but it also wastes energy and adds significantly to the level of pollutants in the building. Fixing this must be the first priority. Once this has been achieved, the installation of a continuous IAQ monitoring system becomes a viable proposition. Ideally, such a system will be linked directly to the HVAC system, thereby effecting control without human interference. The only problem with this is that a typical BMS installation is unlikely to be able to interpret the range of information being generated, and even less likely to have the sophisticated control algorithms necessary to achieve the right outcome.

What is needed is a control system that employs a number of complementary control elements to automatically modulate the volume of incoming air, accurately control the moisture removal process and subsequent re-heating of distributed air, control the re-circulation of exhausted air and manage energy recovery. The installation of this type of control system in a building also has the added benefit of reducing the energy consumption of its air conditioning system.

Wargocki posits the view that savings of between five per cent and 27% have been observed in commercial buildings, where an approach similar to the one mentioned above has been adopted.

To counter the effects of high levels of VOCs, special paints are available that, once applied to walls, will neutralise VOCs. Highly effective filter systems will remove dangerous particulates, and non-chemical decontamination systems will remove biological agents before the conditioned air enters the ductwork. Finally, a mould remediation plan should be adopted, firstly to neutralise any existing mould, secondly to remove affected material from the building and thirdly to protect against further recurrence.

CONCLUSIONS

• Good IAQ is a vital factor in maintaining the health and well-being of occupants in buildings. The olfactory sense is very important, psychologically as well as physiologically. The air we breathe ultimately affects the efficiency and effectiveness of our thinking and day-to-day functions.

• From a commercial perspective, unhealthy buildings result in a loss of productivity, with every work-hour lost typically costing as much as a kilowatt hour of energy. Hence, the occupants’ well-being in monetary terms can be even more important than energy use.

• The education of our children is important. So why compromise it by allowing poor IAQ to adversely affect their learning ability?

• The process of achieving good IAQ is a continual one, throughout the design, construction, commissioning, facilities management and renovation stages of a building’s life. The latest building regulations will help to ensure that new buildings offer better IAQ, but it is the Existing Building stock that really requires our undivided attention.

David O’Riley is Managing Partner, Britannia International. He can be contacted at david@britimc.com.

CPI Industry accepts no liability for the views or opinions expressed in this column, or for the consequences of any actions taken on the basis of the information provided here.